NC-2009 IEQp1: Minimum IAQ Performance

Baseline for outdoor air ventilation

This prerequisite establishes a baseline for providing a minimum amount of outdoor air to buildings in order to maintain good indoor air quality and keep occupants comfortable and healthy. This prerequisite references ASHRAE 62.1-2007 (with errata but without addenda) and is often more stringent than local building codes, although it is not likely to entail any added costs.

Two cases, both may be needed

The compliance paths for mechanically ventilated and naturally ventilated spaces, Case 1 and Case 2, are somewhat different and you may need to follow both paths for the same building. Naturally ventilated spaces must follow the distinct requirements set out in Case 2, even if other spaces in the same building are mechanically ventilated and are following Case 1. Mixed-mode spaces (with both mechanical and natural ventilation) must follow the compliance path for mechanical ventilation, Case 1.

New construction additions will need to confirm that any ventilation systems serving the project meet the ventilation rates required by ASHRAE 62.1 2007, even if the ventilation system design itself is outside the scope of the project. If base building systems do not meet the standard’s requirements, you will need to either modify the base building system or provide detailed analysis documenting the constraints and explaining why the base building systems cannot be upgraded.

ASHRAE 62.1: 2007 vs. 2004

The 2007 edition of ASHRAE 62.1 combines 62.1-2004 and the eight approved and published addenda to the 2004 edition. The new edition does the following:

Clarifies dehumidification analysis requirements and offers exceptions to the 65% relative humidity limit requirement and to the net-positive intake-airflow requirement.

Updates references and clarifies the text particularly as related to subjective evaluation of air quality.

Updates information to be consistent with the U.S. EPA National Ambient Air Quality StandardsThe level of pollutants prescribed by regulations that are not to be exceeded during a given time in a defined area. (EPA).

Includes a new appendix that summarizes the documentation requirements in the body of the standard, thus providing a single point of reference for users.

Requires proper design for buildings that contain both ETSEnvironmental tobacco smoke (ETS), or secondhand smoke, consists of airborne particles emitted from the burning end of cigarettes, pipes, and cigars, and is exhaled by smokers. These particles contain about 4,000 compounds, up to 50 of which are known to cause cancer. and ETS-free areas, by requiring classification of areas based on expected presence of ETS, pressurization of ETS-free areas, separation of ETS and ETS-free areas, and cautionary signage for ETS-areas.

FAQs for IEQp1

A building has fan-assisted ventilation and no mechanical cooling system. Does this qualify as natural ventilation?

If the building relies on the fans for daily ventilation, it is considered a mechanically ventilated building.

Is outdoor air quality testing required in a space using natural ventilation?

Testing in naturally ventilated spaces is not required per 62.1-2007 Sections 4-7 if the outdoor air quality adequately meets 62.1-2007, Table 4-1.

For a space designed to be naturally ventilated, can operable windows or vents be used to satisfy the 62.1-2007 requirements?

Both operable windows and vents can be used, but only the operable area within those elements can be counted towards the minimum percentage (4%) of net occupiable area.

Legend

Best Practices

Gotcha

Action Steps

Cost Tip

Pre-Design

Determine likely ventilation strategies during preliminary programming: natural, mechanical, or mixed-mode ventilation. This prerequisite is attainable with any of these strategies.

This prerequisite is paired with IEQc2: Increased Ventilation. If ventilation rates are targeted above the 30% ASHRAE requirement, projects can gain both the prerequisite and a point for EQc2. Projects pursuing IEQc2 may follow the compliance path for natural ventilation found in Chapter 2 of The CIBSE Applications Manual 10 (AM10) for both the prerequisite and for the credit.

Many of the strategies that contribute to meeting this prerequisite also support earning other indoor environmental quality credits and should be explored as integrated solutions. See LEEDuser's guidance on the rest of the IEQ section for ideas.

Natural ventilation strategies can reduce costs. Natural ventilation in particular can reduce the need for mechanical equipment as well as operational costs. Displacement ventilation, in which air is delivered at or near floor level at a low velocity, can also reduce ducting and improve equipment efficiency. In choosing a system, analyze life cycle cost tradeoffs.

Check local building codes to determine requirements. The project must either meet ASHRAE 62.1-2007, or local codes if they are more stringent. Since ASHRAE 62.1-2007 is often more stringent than local codes, be sure to review and be familiar with its requirements.

This prerequisite is not likely to require added costs.

Case 1: Mechanically Ventilated Spaces

ASHRAE 62.1 recognizes two procedures to prove IAQ compliance: the IAQ Procedure methodology and the Ventilation Rate Procedure. The Ventilation Rate Procedure is easier to apply and is the prescribed path for this LEED prerequisite.

If you are pursuing IEQc5: Indoor Chemical and Pollutant Source Control, you must incorporate MERV 13 filters into your filtration system. These relatively tight filters may affect the fan power and fan sizes necessary to provide the required quantities of air. Involve the engineer early if pursuing IEQc5.

Demand-controlled ventilation can greatly reduce energy use while providing large amounts of fresh air to occupants.

Case 2: Naturally Ventilated Spaces

Determine whether natural ventilation is feasible based on the project type, use, and climate. Study the natural conditions of the site, such as prevailing wind direction, and orient the building to maximize airflow.

An integrated design meeting will help determine whether natural ventilation is a high priority and should be a primary driver of the design process.

Airflow modeling early in the design process can help teams create a more effective natural ventilation design. If the data is used early in the design to help inform team on such thing as space planning and building envelope design. An airflow modeling professional may add some upfront costs, while likely improving system efficiency and effectiveness.

Consider the cost implications of natural ventilation. Passive strategies may reduce or eliminate the need for fans and HVAC equipment, but they may also require high quantities of operable windows and a floor plan that is conducive to passive ventilation. Natural ventilation often requires the cooperation of occupants, to open and close windows when appropriate, for example, be sure that your project is likely to succeed in this respect.

Schematic Design

Separately evaluate each space to determine air requirements and what type of ventilation will be best. Metabolic rate of the space activities and the occupant density are factors that determine the amount of fresh air needed in a space. For example, exercise rooms and conference rooms require more fresh air than offices.

An integrated design approach among the mechanical engineer, architects, owners and occupants will facilitate design decisions that impact the HVAC design. For example, space planning decisions will impact the architectural programming of the space as well as access to natural ventilation.

Increasing a project’s ventilation rate brings long-term cost benefits. Good indoor air quality can lower operational costs by increasing occupants’ health and productivity as well as the value and marketability of the building.

For mixed-mode and naturally ventilated spaces, the mechanical engineer should calculate the outdoor airflow rate and communicate the area requirements for operable wall or roof openings to the architect.

The mechanical engineer begins preliminary ventilation rate calculations during project programming in order to set ventilation quality goals for particular spaces and occupancies. The area of a given multi‐zone system should be broken down by ventilation zones, and all zones within that system must meet the minimum breathing zone ventilation air requirements as per ASHRAE 62.1‐2004. For a typical office space, the mechanical design consists of multiple ventilation zones for which compliance would need to be shown on an individual basis.

Case 1 Mechanically Ventilated Spaces

For mixed-mode ventilation, zone the plan into areas—mechanically ventilated and naturally ventilated—and follow separate compliance calculations for each area.

Case 2 Naturally Ventilated Spaces

Determine the applicable floor area for operable wall or roof openings according to ASHRAE 62.1-2007 section 5.1.

Expect upfront modeling fees for Computational Fluid Dynamics (CFD), but also consider the benefits of CFD modeling: a better-designed natural ventilation system that can bring short-term payback from reduced mechanical systems, and long-term operational savings.

At the first integrated design meeting during schematic design, develop a detailed natural ventilation strategy involving goals for windows, building orientation, space planning, use of atriums, and other access to natural ventilation. Natural ventilation systems may require a more robust and intense integrated design process, of several focused workshops analyzing several alternatives. Computer modeling may be necessary to test various design alternatives to determine which is most effective and efficient.

Hotel and multifamily projects may have difficulty achieving this prerequisite if they are naturally ventilated and have interior spaces that are further than 25 feet from an operable wall or roof opening. These projects might consider increased window areas, shallower floor plates, or using mixed-mode ventilation so that mechanically supplied outdoor air can support areas outside the 25-foot natural ventilation boundary.

Design Development

The mechanical engineer continues to run ventilation rate calculations during the mechanical design process to inform design development and confirm compliance with this prerequisite. The ventilation rate procedure is explained in section 6 of ASHRAE 62.1-2007. See the attached 62MZ calculator.

Continuing to use an integrated design approach among the mechanical engineer, architects, owners and end users will facilitate design decisions that impact the mechanical design. For example, space planning decisions will impact the architectural programming of the space as well as access to natural ventilation.

Strategically locate air intakes for mechanical or natural ventilation systems to avoid taking in contaminants and odors like vehicle exhaust from parking lots or fumes from garbage storage areas.

Incorporating operable windows into the design for natural and mixed-mode ventilation can help with an additional LEED point for EAc6.1: Controllability of Systems—Thermal Comfort.

Case 1: Mechanically Ventilated Spaces

Continue running ventilation rate calculations during the mechanical design process to confirm compliance with this credit and to inform the design. The ventilation rate procedure is explained in section 6 of ASHRAE 62.1-2007. See the 62MZ calculator.

Avoid oversizing mechanical equipment. Oversized equipment will often increase operating costs and reduce operational efficiency. The correct equipment size will depend on a number of factors, including local climate, total building area, insulation levels, air filtration medium, number of windows and doors, and occupant comfort preferences.

Spaces served by the same VAV (variable air volume) controller can be grouped together in the 62MZ calculator, but grouped spaces should have similar exterior exposure. For example, you can group two perimeter spaces that share a VAV controller, but would want to separate a non-perimeter space even if it shares the same VAV controller.

Laboratory facilities generally require very high ventilation rates. Consider installing separate mechanical systems for lab spaces to maximize return-air mixing. Other strategies may include using a heat exchanger to capture energy from laboratory exhaust, using low-flow or variable-flow fume hoods, minimizing ventilation rates during unoccupied times, or using a dedicated outdoor air system.

The Ventilation Rate Procedure calculation includes occupancy counts based on space types.

Case 2: Naturally Ventilated Spaces

Continue to run calculations and develop flow diagrams to inform the design process and confirm compliance. If you are using a natural ventilation modeler for the project, use the model as a tool to inform design development.

The calculation for operable openings will only apply to the floor area adjacent to the window—25 feet to either side and in front of the opening.

The surface area of window openings must, for compliance with ASHRAE 62.1, be equal to or greater than 4% of the occupied floor area that the design considers naturally ventilated. Multiple windows in aggregate can provide the operable area needed to meet the requirements.

In naturally ventilated multifamily buildings, air infiltration from a pressurized hallway or corridor can contribute to the Ventilation Rate Procedure calculation for areas that do not meet the requirements of ASHRAE 62.1, as long as the corridor is pressurized with outdoor air.

If natural ventilation strategies are integrated into the design, ensure that key elements of the natural ventilation system, such as operable windows, window actuators, controls, operable atrium elements, and solar chimneys, are not compromised during value engineering. Educate decision-makers about the natural ventilation design and the importance of maintaining all the key components. If these elements are altered in a way that compromises natural ventilation rates, the mechanical system may no longer be sized appropriately.

Fill out the LEED credit form and upload all supporting documents to LEED Online.

Use this checklist for naturally ventilated spaces prior to construction to review plans for prerequisite compliance:

Are all floor areas within 25 feet of an operable window?

Do all floor areas within 25 feet of an operable window appear have 4 ft2 of opening per 100 ft2 of floor area?

Is fresh outdoor air mechanically supplied and exhausted for all regularly occupied spaces beyond 25 feet of an operable window?

Do any corridors or entryways fall outside of these naturally or mechanically ventilated areas? If so, develop the design further to supply sufficient ventilation.

Use this checklist for mechanical systems prior to construction to check prerequisite compliance:

Using the mechanical equipment schedule, confirm that outside air is being supplied to mechanically ventilated spaces.

Do you have calculations showing the outside air required by ASHRAE 62.1-2007 for mechanically ventilated spaces separate from naturally ventilated spaces?

Do outside air rates meet or exceed the calculated ASHRAE minimums?

Are all regularly occupied spaces listed in the ASHRAE calculations?

What is the desired MERV filtration? If using a high level of ventilation to meet EQc5, has the mechanical system been sized accordingly?

Operations & Maintenance

Monitor outdoor air delivery periodically to confirm that minimum ventilation rates are being maintained. Implement a maintenance program to ensure that mechanical system components are functioning properly.

Test all dedicated building exhaust systems including chemical areas, bathroom, shower, kitchen, and parking exhaust systems to confirm proper fan speed, voltage, control sequences, and set points as applicable. Provide operations and maintenance personnel with manuals and educate them about any atypical maintenance requirements.

Getting feedback on ventilation performance from occupants through surveys can help to identify potential problems that may become expensive if they go unnoticed.

A documented ventilation performance plan can help ensure that systems reach the expected ventilation thresholds.

In projects with operable windows, occupants may not know when conditions are best for opening the windows. Implement a system so that occupants are informed of when to open and close the windows to achieve designed performance and optimal comfort.

Maintain a building operating plan (BOP) that establishes operating schedules and set points and regularly review these parameters against actual building needs. When developing these parameters, consider both time-of-day and time-of-year variations in optimal temperature requirements and be careful to avoid over-conditioning the building spaces with more ventilation, heating or cooling than is necessary.

Adjust reset and setback temperature settings and calibrate controls and sensors. A Building Automation System (BAS) will allow building managers to adjust, monitor and control temperature set points and air volumes throughout the building from a central location. Direct digital controls (DDC) utilized by the BAS will function more efficiently than older pneumatic controls and help to avoid unnecessary use of HVAC equipment during non-business hours and holidays.

Develop and implement a comprehensive Indoor Air Quality Management Plan using the EPA’s “Indoor Air Quality Building Education and Assessment Model” (I-BEAM).

Assign an IAQ manager. This individual should be responsible for developing and managing the IAQ plan including managing contracts for IAQ related services and communication with building occupants about IAQ related issues.

Conduct an IAQ audit of the building and grounds to determine IAQ status. Use forms provided by I-BEAM to record the basic conditions of the building’s occupied spaces, mechanical systems, and building exterior.

Following the initial audit, the IAQ manager must make periodic inspections to uncover new IAQ issues and monitor the status of previous issues. The I-BEAM tool supplies inspection forms that can be tailored to the project building to facilitate this process.

Establish protocols to manage all significant pollutant sources referenced in I-BEAM that are applicable to the project building.

Ensure that procedures are in place for receiving and responding to IAQ complaints from building occupants. The I-BEAM tool provides sample forms and logs for fielding and recording occupant complaints as well as information about key principles for developing effective communication with building occupants regarding IAQ issues. Strategies for investigating and resolving the issues that trigger occupant complaints are covered by a variety of I-BEAM guidelines.

USGBC

IEQ Prerequisite 1: Minimum IAQ Performance

Required

Intent

To establish minimum indoor air quality (IAQIndoor air quality: The quality and attributes of indoor air affecting the health and comfort building occupants. IAQ encompasses available fresh air, contaminant levels, acoustics and noise levels, lighting quality, and other factors.) performance to enhance indoor air quality in buildings, thus contributing to the comfort and well-being of the occupants.

Requirements

CASE 1. Mechanically Ventilated Spaces

Mechanical ventilation systems must be designed using the ventilation rate procedure as defined by ASHRAE 62.1-2007, or the applicable local code, whichever is more stringent.

OPTION 1. ASHRAE Standard 62.1-2007 or Non-U.S. Equivalent

Meet the minimum requirements of Sections 4 through 7 of ASHRAE Standard 62.1-2007, Ventilation for Acceptable Indoor Air Quality (with errata but without addenda). Projects outside the U.S. may use a local equivalent to Sections 4 through 7 of ASHRAE Standard 62.1-2007.

CASE 2. Naturally Ventilated Spaces

Naturally ventilated buildings must comply with ASHRAE Standard 62.1-2007, Paragraph 5.1 (with errata but without addenda). Project teams wishing to use ASHRAE approved addenda for the purposes of this prerequisite may do so at their discretion. Addenda must be applied consistently across all LEED credits.

Potential Technologies & Strategies

Design ventilation systems to meet or exceed the minimum outdoor air ventilation rates as described in the ASHRAE standard. Balance the impacts of ventilation rates on energy use and indoor air quality to optimize for energy efficiency and occupant comfort. Use the ASHRAE Standard 62.1-2007 Users Manual (with errata but without addenda1) for detailed guidance on meeting the referenced requirements.

FOOTNOTES

1 Project teams wishing to use ASHRAE approved addenda for the purposes of this prerequisite may do so at their discretion. Addenda must be applied consistently across all LEED credits.

Technical Guides

This updated version of the spreadsheet categories dozens of specific space types according to how they should be applied under various IEQ credits. This document is essential if you have questions about how various unique space types should be treated. Up to date, 2nd Edition.

This spreadsheet categories dozens of specific space types according to how they should be applied under various IEQ credits. This document is essential if you have questions about how various unique space types should be treated. This is the 1st edition.

Web Tools

This website contains reports from an extensive EPA modeling study that assessed the compatibilities and trade-offs between energy, indoor air quality, and thermal comfort objectives for HVAC systems and formulated strategies to achieve superior performance.

Software Tools

This is a Microsoft Excel calculator that accompanies the ASHRAE 62.1 reference standard. The calculator allows users to plug in variables for specific project types and run the Ventilation Rate Procedure.

ASHRAE released an app for iPhone, iPod touch, and iPad that allows you to perform comprehensive minimum ventilation calculations for a wide variety of commercial buildings based upon Standard 62.1, using either I-P or SI units. This app is based upon the 62MZCalc.xls. Now, you can make calculations at a meeting and know if your project meets IEQp1 or IEQc2.

Ventilation Rate Table

This example ventilation rate table from 23 High Line provides guidance when developing prerequisite compliance documents for your project.

Samples

Air Riser Diagram

This example air riser diagram from 23 High Line shows the mechanical ventilation supply for the building. It is the ducted diagram showing how air will be supplied to building occupants. Use this as an example for how to document ventilation effectiveness compliance.

Samples

LEED Online Forms: NC-2009 IEQ

The following links take you to the public, informational versions of the dynamic LEED Online forms for each NC-2009 IEQ credit. You'll need to fill out the live versions of these forms on LEED Online for each credit you hope to earn.

856 Comments

Mixed-mode ventilation

Dear all!
How do you show compliance with case 1 for GBCI, mixed-mode ventilation? Copied from the Reference Guide: "Project teams can use any acceptable engineering calculation methodology to demonstrate compliance." That does not sound very clear and like GBCI can reject any calculation.
Any experiences with this part?
Thanks alot in advance,

What is the difference

What is the difference between breathing zoneThe breathing zone is the region within an occupied space between 3 and 6 feet above the floor and more than 2 feet from walls or fixed air-conditioning equipment. (AHSRAE 62.12007) outdoor airflow and room outdoor airflow rate? How do I find the room outdoor airflow rate for bedroom/living room type spaces

Minimum exhaust Rates

Dear all,
We work on a private office building where toilet facilities are composed of several individual toilet rooms.
Reading the ASHRAE 62.1, we are not sure about the occupancy category of these spaces : is it private or public toilets ?

Mechanical Ventilation using local code

Is it a compulsory to design mechanical ventilation by using local code even if ASHRAE Standard is more stringent in order to score IEQ Credit 2: Increased Ventilation?

I got a problem to score IEQ c2 because of this. Although in IEQ p1 it showed that i have complied with IEQ c2 for all mechanical ventilation AHUs (by complete and uploaded AHSRAE Calculator 62MZ), but when i want to complete IEQ C2 form, it showed the opposite result.

Hello-
I haven't submitted for IEQc2 recently, but you should be able to base IEQc2 calculations on ASHRAE 62. I don't believe you will be required to show 30% greater than local code as long as you can show 30% greater than ASHRAE 62.
If there is something in the template that seems to be calculating improperly, you can try submitting an explanation under the Special Circumstances section.

Last time i didn't showed the calculation for 30% of local code requirement. I just showed the calculation from 62MZ and had complied everything. Now, it didn't appeared the same result as my last project even in the same form version. However, will try to submit an explanation under Special Circumstances section.

The vent calcs indicate a total area significantly lessthan Plf2

Can please someone give his/her suggestion on the question I have below ?

I received a comment for (Design Preliminary Submission) ventilation calculations indicate a total area (3,055 sqf) significantly less than plf2 (6219 sqf) for the IEQp1
Our response is;
The areas have been revised to match those of table EAp2-1 and to more closely match the architectural floor plans. 3055 sqf was brought up to 4429 sqf and the areas where are not included are the elevator, stairs, jan closet, small restroom, elect & mech spaces and storages (sum of non-ventilated areas is 1489 sf).

My questions is;
Plf2 shows 6219 sqf
Energy model is based on 5812 sqf
IEQp1 - ventilated area is 4429 sqf ( is this sqf reasonable for resubmission ? Does it need to be same as the energy model ? )

No, you cannot average the load over a period of time longer than your calculated time. ASHRAE 62.1 2007 addendum t specifies that Design zone population shall equal the largest (peak) number of people expected to occupy the ventilation zone during typical usage.

The vent calcs indicate a total area significantly lessthan Plf2

Hi,
I received a comment for (Design Preliminary Submission) ventilation calculations indicate a total area (3,055 sqf) significantly less than plf2 (6219 sqf) for the IEQp1
Our response is;
The areas have been revised to match those of table EAp2-1 and to more closely match the architectural floor plans. 3055 sqf was brought up to 4429 sqf and the areas where are not included are the elevator, stairs, jan closet, small restroom, elect & mech spaces and storages (sum of non-ventilated areas is 1489 sf).

My questions is;
Plf2 shows 6219 sqf
Energy model is based on 5812 sqf
IEQp1 - ventilated area is 4429 sqf ( is this sqf reasonable for resubmission ? Does it need to be same as the energy model ? )

regularly occupied zones

Do we need to include spaces such as corridors, store rooms when computing the outdoor air requirement using the 62MZCalc ? Or do we include only regularly occupied zones in the calculation? Please advice.

Good morning,
you have to consider all occupied spacesOccupied Spaces are defined as enclosed spaces that can accommodate human activities. Occupied spaces are further classified as regularly occupied or non-regularly occupied spaces based on the duration of the occupancy, individual or multi-occupant based on the quantity of occupants, and densely or non-densely occupied spaces based upon the concentration of occupants in the space., and you can exclude inactive space.
Thanks for your attention,
LEEDme

Dear Stella,
You can find answer at IEQ space matrix http://www.usgbc.org/resources/eq-space-type-matrix .
Storage rooms without permanent working places are considered unoccupied.
Egress stairway or dedicated emergency exit corridor are considered unoccupied, otherwise it must be ventilated according to table 6-1 of AHRAE 62.1.

Does mech engineer need to be PE to sign the "signature' box ?

Shall the person who enters his/her initials under signatory section ( for example IEQp1 or EAp2-1, 2-2, 2-3 ) be registered mechanical engineer (PE) ? If so, can you please let me know where this requirement is stated ? There are (2) mechanical engineers are working on the project. They shared the credits and placing their own initials to each credit even though PE overview every document.
Thanks

wall mounted FCUs

Hi,
We are working on a project with wall mounted FCUs. When performing the calculation in 62mZ Cal, what would be the value to input for Ez( Zone air distribution effectiveness at conditioned analyzed), as this is a wall mounted unit and not ceiling unit. Please advise.

CFD based air changes vs mechanical exhaust.

Hey andrew. Do you know how natural ventilation compares to mechanical flow rates?

For example, if I had a bathroom with 100 cfm of required exhaust, does the 4% openings requirement match the achAir changes per hour: The number of times per hour a volume of air, equivalent to the volume of space, enters that space. equivalent to 100cfm?

The 4% opening will not likely be equivalent to the required exhaust rate in most cases. It is possible if you leave the windows open and you are putting air into the room. That being said, the 4% does meet the 2007 requirements.

If you have a preconditioning unit serving your fan coils, and the fan coils each have one ventilation zone then you should use a signle zone system for each fan coil. Any fan coil that serves multiple ventilation zones should use a 62MZ calc. If your precondition unit just supplies fresh air, then there is no reason to treat it all as one large system.

Hi,
How would you determine which system the above posted note is applicable to?
My project has a VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. system, with AHUs serving single and multiple zones. I am not sure if we should use the 62MZCalc or if we can use the Table IEQp1-A.

For the single zone VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. systems, use the table. For the multi-zone systems, use the 62mz calc.

62.1 Theater Stage and Seating - Open spaces - 62.1 vent require

Hi,
I have a theater space which has one single zone AHU1.Air-handling units (AHUs) are mechanical indirect heating, ventilating, or air-conditioning systems in which the air is treated or handled by equipment located outside the rooms served, usually at a central location, and conveyed to and from the rooms by a fan and a system of distributing ducts. (NEEB, 1997 edition)
2.A type of heating and/or cooling distribution equipment that channels warm or cool air to different parts of a building. This process of channeling the conditioned air often involves drawing air over heating or cooling coils and forcing it from a central location through ducts or air-handling units. Air-handling units are hidden in the walls or ceilings, where they use steam or hot water to heat, or chilled water to cool the air inside the ductwork. serving the stage area and one single zone AHU serving the seating. I had modeled these as separate single zone AHU's using the 62.1 calculator however the stage is only provided with 7.5l/s/person which equates to 75l/s. Due to the size of the stage the 62.1 people and area (0.3l/s/m2) rate means 250l/s is required. There is more than enough outside air provided to the seating but does the outside air provided by the stage AHU need to be increased to comply (e.g. there is no workaround with the spaces being open to each other)? There are not fans specifically pulling air from the seating to the stage just the general mixing of the spaces being open to each other.
Thanks
Victoria

Zone Calculation Ds% for VAV System

"The ventilation calculations indicate that the value of the flow rate of air projected under the condition tested (DS) was modeled as 100% level for each of the areas system; however the DS system is typically much lower for systems including VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. terminal units in the worst possible case. For the worst case, the DS can be determined for each area by dividing the minimum volume of the primary air VAV terminal during the worst possible case the peak volume of the VAV air terminal during the maximum cooling."

I'm working on a project, which has raised floor and fan coil air blowing underfloor. I've maded all analysis based on LEED Tool for multizones and considered the 100% Ds% in each zone.

Local Code more stringent - Pre req and IEQc2 documentation

I am working on a large project in Australia that has used local code. The local code is more stringent than 62.1 however needs to be documented for the submission. I was intending on working out some spaces which i deem to be worst case to show the outside air at the unit complies. However the LEED form asks for the required outdoor air intake and needs a baseline to show 30% better from. So I am wondering:

1) Has anyone documented the pre-requisite without doing the full 62.1 calculations to show equivalence
2) Has anyone documented the +30% credit without doing the full 62.1 calculations to show equivalence

Victoria, if you are complying with the more stringent requirements (which exceed ALL of the ASHRAE 62.1 requirements) then you should be fine with meeting the intent of the prerequisite and increased credit. That being said, meeting the intent, and documenting it are much different things. My recommendation is that you simply document using the ASHRAE 62.1 and LEED template. This is a much easier way to attain the credits since the LEED reviewers will be seeing the same thing they always do, and if you need to resubmit, you will be able to get more help.

Commercial Kitchens

A typical commercial kitchen has a large makeup air unit that provides air to a hood over the cooking surfaces, several exhaust fans, and (in our case) a large central cooling-only 0% OA AHU1.Air-handling units (AHUs) are mechanical indirect heating, ventilating, or air-conditioning systems in which the air is treated or handled by equipment located outside the rooms served, usually at a central location, and conveyed to and from the rooms by a fan and a system of distributing ducts. (NEEB, 1997 edition)
2.A type of heating and/or cooling distribution equipment that channels warm or cool air to different parts of a building. This process of channeling the conditioned air often involves drawing air over heating or cooling coils and forcing it from a central location through ducts or air-handling units. Air-handling units are hidden in the walls or ceilings, where they use steam or hot water to heat, or chilled water to cool the air inside the ductwork. that provides cool air to the space.

I am puzzling over how to shoehorn this situation into the 62MZcalc spreadsheet.

Let's say I have 100% OA supply air at the hood of 1700 CFM, exhaust air at the hood of 2100 CFM. You can do the math and see 400 CFM of this exhaust air comes from "somewhere else" (Transfer air?). I am not sure how one handles transfer air in the 62MZcalc spreadsheet. Some fraction of the 1700 CFM hood supply air ends up in the kitchen, most of it gets swept up with the exhaust. 100% OA supply air is delivered at essentially room temperature, but right near the exhaust, so 100% Ez would not be appropriate.

What would you use for Ez zone air distribution effectivess? Would Supply air be "1700 CFM 100% outside air" in this case?

Would it be appropriate to use an Ez of 0.5, for "supply air near exhaust", counting the kitchen hood supply as the fresh air?

First, if the zones served are entirely commercial kitchen zones, my reading of ASHRAE 62.1 indicates the zones are only required to be exhausted, not supplied with outdoor air. I believe compliance with ASHRAE 62.1 is through satisfying the required amount of exhaust air (and making up the air per section 5), not by supplying a specific amount of outdoor air.

If there are non-commercial kitchen zones in the space (eg a managers office, active occupiable storage, etc), these would require their own source of outdoor air.

A second point - we have seen issues shoehorning 100% OA systems into the 62MZ calculator. The calculator is generally for systems that have some recirculated air; if the systems are 100% OA, then they may be documented either in the Appendices of the LEED EQp1 template (generally at the bottom, if the "100% OA" checkbox is selected) or in a custom spreadsheet. While it may seem counter-intuitive, in some cases we've seen the required amount of outdoor air increase when zones were first documented in the 62MZ calculator and then moved to a 100% OA calculator later. I believe this is because the MZ calculator uses equations that do not treat zone air distribution effectiveness in the same way as it is treated in the 100% OA system equations from 62.1.

Thanks, Aaron. I can find an entry for kitchens in Table 6-4 requiring exhaust, no entry for commercial kitchens (and other items from 6-4) in Table 6-1 requiring fresh air. It makes sense that exhaust would be the only requirement, but I haven't found a paragraph in the standard that just comes right out and says this. Maybe a sharper eye than mine can find it?

The closest I can find is paragraph 6.2.8 "... exhaust makeup air can be any combination of outdoor air, transfer air or recirculated air."

Yeah - I doubt the standard will have conclusive language that indicates "this and such space type does not require ventilation" - seems like it will be up to our interpretations of what the standard does say.

If you're looking at the 2007 version of the standard, I've relied on the language in section 5.10.2 to find the requirement that there be enough makeup provided to offset the exhaust, under certain conditions - "for a building, the design minimum outdoor air intake shall be greater than the design maximum exhaust airflow when the mechanical air-conditioning systems are dehumidifying."

Ventilation Effectiveness

I am working for a client who has a variable refrigerant HVAC system with a separate fully condition ventilator supplying fresh air. They are over budget and the contractor is proposing ducting the air into the back of the units in lieu of separate ducts for the ventilation system. We are worried that this would lead to them not meeting the LEED IEQ prerequisite. Would they not meet the prerequisite because it is already fully conditioned and not just a heat exchanger?
I am trying to understand how outside air loses effectiveness and would require more. In an effort to maximize the potential energy savings and minimize first costs (reduced unit size and main ductwork sizes as part of the shell package) the outdoor airflow quantity was based on a ventilation effectiveness of 1.0.
In this case that meant space delivered neutral air. If the air were ducted to the back of each unit it would be heated to a temperature that reduces the effectiveness to 0.8, thus requiring more total outdoor air.
Would this change of effectiveness hurt our chances of obtaining the LEED IEQ prerequisite related to ASHRAE 62.1?

Dustin, I believe you are correct. If the air is heated, the effectiveness would be reduced to 0.8. The outside air design requirement would need to be based on an Ez value of 0.8 instead of 1.0. You will need to update your calculations with 0.8 and see how much outdoor air is required with the new configuration.

Thank you Ilona. Would the change in effectiveness to 0.8 from 1.0 result in the loss of the LEED IEQ prerequisite? Would some sort of system change alleviate this issue and still maintain compliance with the prerequisite?

Dustin, I think you would have to run the numbers to confirm, but yes, if your outside air system was designed with an Ez value of 1 and you now switch to an Ez value of 0.8, you may not have enough outside air. This would hurt your chances of meeting the prerequisite. Your options are to a) ask the contractor to stick to the initial project design which requires direct delivery of outside air b), increase the volume of outside air provided by the AHU1.Air-handling units (AHUs) are mechanical indirect heating, ventilating, or air-conditioning systems in which the air is treated or handled by equipment located outside the rooms served, usually at a central location, and conveyed to and from the rooms by a fan and a system of distributing ducts. (NEEB, 1997 edition)
2.A type of heating and/or cooling distribution equipment that channels warm or cool air to different parts of a building. This process of channeling the conditioned air often involves drawing air over heating or cooling coils and forcing it from a central location through ducts or air-handling units. Air-handling units are hidden in the walls or ceilings, where they use steam or hot water to heat, or chilled water to cool the air inside the ductwork.. If you are hunting for other options, I suppose you could try to change the supply air configuration to reduce temperature stratification. But at that point, you might as well just ask the contractor to install the system the way it was originally designed!

IEQp1:Heating mode

Hi,
Our project is located in Asia with a tropical climate. When we submitted our calculations for IEQp1: Minimum Indoor Air Quality Performance; the assessor came back with the following comment:
It appears that the calculations may not have been performed for the worst-case conditions. Generally, worst-case conditions are during heating mode;Provide revised Ventilation Rate Procedure calculations for zone air distribution effectiveness, Ez, of 0.8 (for an overhead distribution system in heating mode) and when the VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. system is at minimum flow.
My question is why we need to do calculations during heating mode as we do not use heating during any part of the year.

If your building does not have heating, then you just need to write a response to the reviewer that says your building does not have heating. An Ez value of 1.0 is appropriate if your system is only cooling.

However, if you have VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. boxes that vary the flow rate to the space, then you still need to make sure you evaluate the system at minimum expected flow rate.

Hi Ilona,
Thanks for the info. Where do we input the minimum expected flow rate in the IAQIndoor air quality: The quality and attributes of indoor air affecting the health and comfort building occupants. IAQ encompasses available fresh air, contaminant levels, acoustics and noise levels, lighting quality, and other factors. spreadsheet? is it Ep (Primary air fraction of supply air at conditioned analyzed) ?

If you have basic VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. boxes that modulate airflow from the air handling unit, then you would enter the percent airflow next to DS "Percent of total design airflow rate at condition analyzed."

Ep is only applicable for alternate systems such as induction units, where the supply air is a mix of recirculated air and primary air.

Hi Ilona,
Thanks. Yes we do have VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. boxes and we had entered the percent airflow next to DS as 100%,since we are using VAV boxes & operated only by cooling mode.
so i am not sure of what the assessor means as "when the VAV system is at minimum flow"? do i need to need to change the percentage?where do i get that value from?

Stella,
If you have VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. boxes, the supply air to your zone will only be 100% when you are at peak cooling on the hottest and sunniest day of the year when your space is fully occupied. During other times, say early in the morning or while the sun is blocked by clouds, your space won't need as much cooling. At that point, your VAV boxes will modulate to reduce the airflow to the space. Since the airflow to your space is reduced, the outdoor air to your space will also be reduced. That's why the reviewer wants you to evaluate the system at worst-case conditions. You need to determine the minimum setting on your VAV boxes and use that for the value of Ds.

Just to add to what Ilona said, the spaces that are not critical zones should be reduced as well. The 62MZCalc takes into account the unused OA that is recirculated from spaces that receive more OA than necessary. When those zones are reduced, the OA requirement is increased for the system.

Thanks Ilona & Andrew for your clarifications.
The VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. will be at the minimum setting when the occupancy load is less, as it is controlled by the CO2Carbon dioxide sensors. So if we require to do calculations when the VAV is set at the minimal supply, then do I need to alter my occupancy load too? Appreciate your help!

The VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. setting in the calculation should be altered based on the airflow to the room changing due to temperature. In almost all VAV applications, the aiflow changes based on a demand for more or less cooling. In the case of a cold day (no cooling load), and an occupied room, it is likely that you will be at minimum airflow and maximum occupancy.

Your calculation needs to represent your actual building use. If the above is not a true case then you need to write a narrative as to why it is not. In the past, I have had conference rooms on a middle floor in the center of the building (no envelope load) and have not decreased the supply flow since the cooling load is based on the occupants only.

So in order to compute the worst case scenario i understand that i need to change the value for Ds to reflect the minimum setting on the VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. box. Are there any other parameters that i need adjust in the 62MZCalc ? As i believe if i am going to change the Ds to a lower % the fresh air requirement will be more.Do i need to adjust the total design air supply too?
Forgive me for my ignorance. Thanks.

100% OA multiple zones system

We are currently working on a project including an 100% OA AHU1.Air-handling units (AHUs) are mechanical indirect heating, ventilating, or air-conditioning systems in which the air is treated or handled by equipment located outside the rooms served, usually at a central location, and conveyed to and from the rooms by a fan and a system of distributing ducts. (NEEB, 1997 edition)
2.A type of heating and/or cooling distribution equipment that channels warm or cool air to different parts of a building. This process of channeling the conditioned air often involves drawing air over heating or cooling coils and forcing it from a central location through ducts or air-handling units. Air-handling units are hidden in the walls or ceilings, where they use steam or hot water to heat, or chilled water to cool the air inside the ductwork. providing ventilation to 3 different areas.
The same people (110 people on peak) will be moving between those 3 areas during the day.

Using the table in the form for 100% OA is leading to a very large amount of outside air to provide since the number of people in each area for the calculation is 110.
Actually, we want to size the AHU to provide the required minimum OA for this zone composed of 3 areas and occupied by 110 ppl max. Depending on the need, the adequate volume of air will be directed toward each areas based on CO2Carbon dioxide sensors.

Andrew, thank you but there is actually no diversity as the Ahu1.Air-handling units (AHUs) are mechanical indirect heating, ventilating, or air-conditioning systems in which the air is treated or handled by equipment located outside the rooms served, usually at a central location, and conveyed to and from the rooms by a fan and a system of distributing ducts. (NEEB, 1997 edition)
2.A type of heating and/or cooling distribution equipment that channels warm or cool air to different parts of a building. This process of channeling the conditioned air often involves drawing air over heating or cooling coils and forcing it from a central location through ducts or air-handling units. Air-handling units are hidden in the walls or ceilings, where they use steam or hot water to heat, or chilled water to cool the air inside the ductwork. will be 100% OA.

Ok. I thought that the 100%OA unit was providing preconditioned air to recirculating units. In that case, without demand contol ventilation or a recirculation mode, you will need to use the calculated flow.

If the areas will not be occupied often, and it's not an exhaust driven space, then it's a good idea to recirculate sometimes or use a time averaged ventilation rate.

I believe that the maximum airflow would be the correct value to use. The CO2Carbon dioxide sensor is designed to limit airflow when the space is unoccupied, and not needing any outside air. ASHRAE 62 vbentilation rates are based on maximum occupancy. The CO2 sensour is designed to sense maximum occupancy and turn on the outside air at that time, so it would make sense to analyze the peak airflow through the damper.

Natural ventilation

We are working on a residential core and shell project, and we are having some issues with the compliance of ASHRAE 62-1 ventilation requirements.
Basically, the building has apartments on each long side and a central corridor that goes all the way through.
All of the rooms include a operable window of 4% of the area within 25 feet, except a small service room that would only have a window to the corridor; therefore it would be ventilated through the adjoining space. Now, this central corridor is completely open to the outdoors on its sides; could we use the 4% rule, or do we need to go with 8% or 25ft2 minimum? The problem is that a 25ft2 window on that tiny space would be unreasonable.
Thank you for your comments.

Do you know which LEED credits have the most LEED Interpretations and addenda, and which have none? The Missing Manual does. Check here first to see where you need to update yourself, and share the link with your team.